Multiple Tuned Liquid Dampers for Efficient and Robust Structural Control

Abstract

In traditional tuned liquid damper (TLD) installations, TLD tank(s) are tuned to a single optimal frequency as determined by well-known dynamic vibration absorber theory. A multiple tuned liquid damper (MTLD) is created when the sloshing frequencies are distributed over a range near the structural frequency. In this paper, an equivalent mechanical model for a structure–MTLD system is developed. A third-order nonlinear multimodal model is employed to assess nonlinear fluid affects and serve as independent model verification. To the authors’ knowledge, this is the first time the nonlinear energy dissipation associated with damping screens and the nonlinear coupling amongst sloshing modes has been considered for MTLD systems. MTLD systems consisting of one (traditional TLD), two, and three tanks are used to reduce the resonant response of a single degree of freedom structure. The MTLD provides structural control that is superior to a traditional TLD. The MTLD is less sensitive to the structural excitation amplitude, which enables the device performance to be maintained at low amplitude excitations associated with common wind events. The MTLD is also shown to be more robust to changes to the structure’s natural frequency than the traditional TLD. Since many TLD installations require multiple tanks to satisfy space restrictions, the findings of this paper are highly relevant to structural engineering. This paper shows that by slightly altering the fluid depth of each tank, improved structural control performance can be achieved at little additional cost.